The present invention relates a liquid crystal display device useful for a liquid crystal projector which illuminates a liquid crystal display element with light from a light source and projects images on the liquid crystal display element on a screen.
Recently, liquid crystal display devices have been widely used in small-sized display devices, display terminals for office automation equipment and the like. Basically, a liquid crystal display device includes a liquid crystal display panel (also called a liquid crystal display element or a liquid crystal cell) composed of a pair of insulating substrates at least one of which is made of a transparent plate, a transparent plastic plate or the like, and a layer of liquid crystal composition (a liquid crystal layer) sandwiched between the insulating substrates.
The liquid crystal display devices are divided roughly into the simple-matrix type and the active matrix type. In the simple-matrix type liquid crystal display device, a picture element (hereinafter a pixel) is formed by selectively applying voltages to pixel-forming strip electrodes formed on both of the two insulating substrates of the liquid crystal display panel, and thereby changing orientation of a portion of liquid crystal molecules of the liquid crystal composition corresponding to the pixel. On the other hand, in the active-matrix type liquid crystal display device, the liquid crystal display panel is provided with signal lines, pixel electrodes, reference voltage electrodes and active elements each associated with one of the pixel electrodes for pixel selection which are formed on one of the substrates, and a pixel is formed by selecting the active element associated with the pixel and thereby changing orientation of liquid crystal molecules present between a pixel electrode connected to the active element and the reference voltage electrode associated with the pixel electrode.
Generally, the active matrix type liquid crystal display device employs the so-called vertical electric field type in which an electric field for changing orientation of liquid crystal molecules is applied between an electrode disposed on one of a pair of opposing substrate and another electrode disposed on the other of the opposing substrates. Also put to practical use is the so-called horizontal electric field type (also called IPS (In-Plane Switching) type) liquid crystal display device in which an electric field for changing orientation of liquid crystal molecules is applied in a direction approximately in parallel with the major surfaces of the opposing substrates.
Among display devices employing the liquid crystal display device, a liquid crystal projector has been practical use. The liquid crystal projector illuminates a liquid crystal display element with light from a light source and projects images on the liquid crystal display element on a screen. Two types, a reflective type and a transmissive type, of liquid crystal display elements are usable for liquid crystal projector. The reflective type liquid crystal display element is capable of being configured to make approximately the entire pixel area an useful reflective area, and consequently it has advantages of its small size, high definition display and high luminance over the transmissive type liquid crystal display element.
Consequently, a small-sized high-definition liquid crystal projector can be realized by using the reflective liquid crystal display element without decreasing its luminance.
A reflective liquid crystal display element is disclosed in U.S. Pat. No. 5,978,056 issued on Nov. 2, 1999, for example. U.S. Pat. No. 5,978,056 discloses a multilayer light blocking film, but does not disclose the arrangement of two light blocking films spaced from each other in a direction of their thickness.
The liquid crystal projector has problems of miniaturization, and increasing of resolution and luminance. To solve the problems, the liquid crystal display element used for the liquid crystal projector needs to be further reduced in size, and further increased in resolution and luminance. In reducing the size and increasing the resolution and luminance of the transmissive type liquid crystal display element, it is inevitable that the ratio of a light-transmissive area to the entire area in one pixel (hereinafter the aperture ratio) is reduced considerably.
It is an object of the present invention to provide a reflective liquid crystal display device capable of increasing its luminance, it is another object of the present invention to provide a reflective liquid crystal display element featuring a high image quality, and it is still another object to provide a liquid crystal display element featuring a high image quality by prevention of entering of unwanted light occurring therein and high light utilization efficiency obtained by a higher aperture ratio, and to provide a liquid crystal projector employing the liquid crystal display element.
In accordance with an embodiment of the present invention, there is a liquid crystal display device comprising: a first substrate; a second substrate; a liquid crystal layer sandwiched between the first substrate and the second substrate; a plurality of reflective electrodes arranged on a surface of the first substrate on a liquid crystal layer side thereof, each of the plurality of reflective electrodes being adapted to be supplied with a video signal; and a plurality of light-blocking conductive films disposed below the plurality of reflective electrodes with an insulating layer interposed between the plurality of light-blocking films and the plurality of reflective electrodes, each of the plurality of light-blocking films being electrically connected to a corresponding one of the plurality of reflective electrodes, each of the plurality of light-blocking films being disposed to cover at least a portion of spacings between the corresponding one of the plurality of reflective electrodes and ones of the plurality of reflective electrodes adjacent to the corresponding one of the plurality of reflective electrodes.
In accordance with another embodiment of the present invention, there is a liquid crystal display device comprising: a driving-circuit substrate; a transparent substrate; a liquid crystal layer sandwiched between the driving-circuit substrate and the transparent substrate; a plurality of reflective electrodes arranged on a surface of the driving-circuit substrate on a liquid crystal layer side thereof; a plurality of semiconductor switching elements disposed below the plurality of reflective electrodes, each of the plurality semiconductor elements being configured to supply a signal to a corresponding one of the plurality of reflective electrodes; a first light-blocking film for covering the plurality of semiconductor switching elements; and a plurality of second light-blocking films each disposed to cover at least a portion of spacings between adjacent ones of the plurality of reflective electrodes.
In accordance with another embodiment of the present invention, there is a liquid crystal display device comprising: a first substrate; a second substrate; spacers made of resin for establishing a spacing between the first substrate and the second substrate; a peripheral frame made of the resin and interposed between the first substrate and the second substrate; a liquid crystal component filled in a spaced enclosed by the first substrate, the second substrate and the peripheral frame; a plurality of reflective electrodes arranged on a surface of the first substrate on a liquid crystal layer side thereof; a plurality of dummy electrodes disposed between the plurality of reflective electrodes and the peripheral frame, each of the plurality of dummy electrodes being supplied with a dummy-electrode signal; a plurality of semiconductor switching elements disposed below the plurality of reflective electrodes, each of the plurality semiconductor elements being configured to supply a signal to a corresponding one of the plurality of reflective electrodes; a first light-blocking film for covering the plurality of semiconductor switching elements; and a plurality of second light-blocking films each disposed to cover at least a portion of spacings between adjacent ones of the plurality of reflective electrodes.